An ever-increasing number of applications (i.e., computer software) with various features are available to users of personal computers. Users can tailor the operation of these applications to suit their needs by specifying various configuration parameters. For example, a browser application may have a configuration parameter that provides a URL of a web page that is displayed initially whenever the browser application starts (i.e., “a home page”). The browser application may also have configuration parameters that identify what programs are to be invoked to process certain types of content (e.g., a “jpeg” file) and that contain passwords of the user that are to be used when the application connects to various servers. The values of the configuration parameters can be stored in application-specific configuration files such as UNIX resource files, or can be stored in a central registry such as the Windows® registry file. The applications access these files to retrieve the values of the configuration parameters.
If certain configuration parameters have incorrect values, then the applications may exhibit an undesired behavior. For example, if the value of a home page configuration parameter is not set correctly, then when the browser application starts, it will exhibit an undesired behavior by not displaying a home page or displaying the wrong home page. If a configuration parameter incorrectly indicates a certain text editor should be invoked to process a graphics file, then the undesired behavior will be the incorrect displaying of the graphics content. Similarly, if a password configuration parameter has the wrong password, then the failure to connect to the server will be the undesired behavior.
Because of the complexity of applications and their large number of configuration parameters, it can be very time-consuming to troubleshoot which configuration parameters are at fault for causing an application to exhibit the undesired behavior. Most users of personal computers have difficulty performing this troubleshooting. As a result, users typically rely on technical support personnel to assist in the troubleshooting. Not only is this troubleshooting expensive but also users may experience a significant productivity loss as a result of their inability to effectively use an application that is exhibiting an undesired behavior.
Typically, technical support personnel use an ad hoc approach to troubleshoot configuration problems. The personnel using knowledge gained from experiencing similar problems will try to narrow in on the at-fault configuration parameter. This ad-hoc approach can take a considerable amount of time and even longer if it is a combination of configuration parameters whose values are incorrect. In some cases, the technical support personnel may compare the values of the configuration parameters to “ideal” values for that application. Because of the large number of configuration parameters available and large number of possible values for each configuration parameter, many of the configuration parameters will have no “ideal” value. Thus, technical support personnel may still need to review the values of all the configuration parameters that could possibly be at-fault configuration parameters.
A troubleshooting system for automatically identifying a configuration parameter that is at fault for causing an application to exhibit an undesired behavior is described in U.S. patent application Ser. No. 10/918,786, entitled “Method and System of Troubleshooting a Misconfiguration of a Computer System based on Configurations of Other Computer Systems” and filed on Aug. 13, 2004, which is hereby incorporated by reference. That troubleshooting system collects configuration information (e.g., configuration parameter names and their values) from computer systems that may have the same application installed. The troubleshooting system then analyzes the configuration parameters of the application that is exhibiting the undesired behavior and the configuration parameters collected from the other computer systems. Based on this analysis, the troubleshooting system identifies which configuration parameter is likely to be at fault for causing the undesired behavior.
The retrieving of configuration information from other computer systems may raise privacy and integrity issues. The privacy issues may relate to configuration information, such as listings of web sites visited, passwords, and so on, that a user may not want to divulge. The integrity issues arise when a computer system lies about its configuration information. The lie may be promulgated because the user of the computer system is malicious or because the integrity of the computer system has been compromised such as by a virus or worm.
A system for retrieving information from computer systems in a way that addresses privacy and integrity issues is described in U.S. patent application Ser. No. 10/918,086, entitled “Method and System for Collecting Information from Computer System based on a Trusted Relationship,” and filed on Aug. 13, 2004, which is hereby incorporated by reference. The retrieval system is implemented on a network of devices that communicate with each other via a secure communications link. Each device is directly connected to one or more “friend” devices that it trusts. The retrieval system operates by forwarding a request for data from one friend device to another friend device. Each friend device may optionally add data to the request until all the requested data is added. The request is then returned to the device that initiated the request. The retrieval system defines requests that do not include a history of the devices through which a request has traveled; that is, the requests are “historyless.” As a result, a device will only know for sure that a particular request traveled through the friend devices from which it received the request and to which it forwarded the request. In addition, because devices may or may not add data to a request, a device that receives a request from a friend device will not know whether the request includes data of the friend device. Because each device selects the next device to which to send a request, the requests do not identify the devices that will add data; that is, the requests are “futureless.”
This retrieval system may, however, be susceptible to privacy-compromising attacks such as gossip attacks and polling attacks. A gossip attack occurs when a device contributes data to a request and the previous friend device and the next friend device collude to determine the data contributed by the device. A polling attack occurs when a friend device repeatedly sends fake requests for data to a device indicating that data from only one more device is needed to determine the data contributed by the device. To help foil both of these types of attacks, the device may only contribute data to the request based on predetermined probability function. Nevertheless, the attacking “friend” devices may still be able to guess the contributed data using some statistical analysis.